Light sensor attachment structure of image display device

ABSTRACT

Provided is an optical sensor mounting structure which is used in an image display device and in which the gap between a reflection sheet and a tubular cushion for preventing the entry of external light into an optical sensor is eliminated so that the amount of light from a backlight can be measured accurately. A liquid crystal image display device includes an optical sensor that measures light from the back surface of a reflection sheet, a substrate having the optical sensor thereon, and a tubular cushion for preventing the entry of external light into the optical sensor. The front surface of the tubular cushion is bonded to the reflection sheet, and the back surface thereof is bonded to the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/613,457, filed on Jun. 5, 2017, which is a divisional of U.S. patentapplication Ser. No. 14/770,016, filed on Aug. 24, 2015, now abandoned,which is a national phase application of International application No.PCT/JP2013/073089, filed on Aug. 29, 2013, which based upon and claimsthe benefit of priority from Japanese patent application No.2013-034517, filed on Feb. 25, 2013.

TECHNICAL FIELD

The present invention relates to an optical sensor mounting structurefor use in image display devices.

BACKGROUND ART

Image display devices such as liquid crystal displays, organicelectroluminescent displays, and plasma displays provide high-definitionimage quality with low power consumption. Such image display devices arealso slim due to the flat screens thereof. These image display devicesare being used not only in offices or households but also at sites ofvarious kinds of professional work, such as graphic design and medicalcare.

In a liquid crystal image display device, the reproducibility of thedisplay image is increased, for example, by measuring light from theback surface of a reflection sheet disposed behind a backlight in animage display unit to control the luminance of the backlight.

Patent Literature 1 discloses that an optical sensor for detecting lightof a backlight leaking from a reflection sheet is disposed over the backsurface of a liquid crystal display unit (in Claim 1 thereof). It alsostates that a photodetector includes a cushion member for guiding onlylight leaking from the reflection sheet to the optical sensor and thatthe cushion member is a donut cushion and is in close contact with aliquid crystal module to shield light.

Patent Literature 2 discloses that a luminance sensor is mounted on anaperture formed in the back surface of a casing and that a reflectionsheet also has an aperture as necessary.

Patent Literature 3 discloses that an optical sensor is mounted over theback surface of a chassis with a base therebetween, that a circular holehaving a diameter of 3 mm is formed as a reflection sheet hole in areflection sheet which lies in front of the optical sensor, and that acircular hole having a diameter of 30 mm or less is formed as a chassishole in the chassis, which lies in front of the optical sensor.

Patent Literature 4 discloses the following image display device: theimage display device includes a reflection sheet disposed on the backsurface of a backlight lamp and configured to reflect light emitted fromthe backlight lamp forward, an optical sensor disposed on the backsurface of the reflection sheet and configured to detect lightintroduced through a first aperture formed in the reflection sheet, anda control unit that controls the luminance of the backlight lamp on thebasis of the detection result of light applied to the optical sensor; asensor holder housing the optical sensor is disposed on the back surfaceof the reflection sheet; the sensor holder has a second aperture havinga smaller area than that of the first aperture in the inner region ofthe first aperture; the sensor holder also has a reflection part on asurface which is near the reflection sheet adjacent to the secondaperture and which is exposed from the first aperture; and light fromthe backlight lamp is introduced into the optical sensor through thefirst and second apertures (in Claim 1 thereof).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 10-222084 (Japanese Patent No. 3171808)

Patent Literature 2: Japanese Unexamined Patent Application PublicationNo. 2000-315596

Patent Literature 3: Japanese Unexamined Patent Application PublicationNo. 2009-014901

Patent Literature 4: Japanese Unexamined Patent Application PublicationNo. 2009-58678 (Japanese Patent No. 4769969)

SUMMARY OF INVENTION Technical Problem

A liquid crystal panel module has a reflection sheet and a panel metalsheet flexibly incorporated therein. Specifically, since the perimeterof the reflection sheet is simply mounted on the edge of the panel metalsheet, portions closer to the center, of the reflection sheet are moreflexible. For this reason, due to the influence of the heat of thebacklight or the like, the reflection sheet becomes deformed, or theamount or manner of the deformation of the originally deformedreflection sheet varies. Through an investigation, the present inventorsfound that the amount of light acquired by the optical sensor increasedor decreased due mainly to such deformation. Liquid crystal imagedisplay devices are currently increasing in screen size or slimming, andthe amount of deformation of the reflection sheet is thought to beincreasing accordingly.

However, Patent Literatures 1 to 4 do not state that the reflectionsheet becomes deformed due to the influence of the heat of the backlightor the like or that the amount or manner of deformation of thereflection sheet varies due to such influence. Further, these PatentLiteratures do not include any description suggesting that the amount oflight acquired by the optical sensor increases or decreases due mainlyto the deformation of the reflection sheet.

Through an investigation, the present inventors found that there weremodels in which even if there was no gap (there is a small gap) betweenthe tubular cushion and reflection sheet in the initial state, thereflection sheet became deformed due to the influence of the heat of thebacklight or the like and thus a gap occurred (or the gap became larger)between the tubular cushion and reflection sheet. The present inventorsalso found that there were models in which even if there was a gap(there was a large gap) between the tubular cushion and reflection sheetin the initial state, the reflection sheet became deformed due to theinfluence of the heat of the backlight or the like and thus the gapdisappeared (or the gap became smaller) between the tubular cushion andreflection sheet. That is, the manner that the reflection sheet becomesdeformed with the temperature is not uniform. The present inventors thenfound that the amount of light from the reflection sheet increased ordecreased according to the presence or absence of the gap or the size ofthe gap and thus the correlation between the change in the luminance ofthe liquid crystal display panel and the value measured by the opticalsensor varied.

FIG. 20 is a schematic front view of a known liquid crystal imagedisplay device 101. FIGS. 21 and 22 are sectional views taken along lineA-A of FIG. 20 and are main part sectional views of the liquid crystalimage display device 101 seen from above. The known liquid crystal imagedisplay device 101 includes a liquid crystal display panel 102, abacklight 103 disposed behind the liquid crystal display panel 102, areflection sheet 104 disposed behind the backlight 103, a panel metalsheet 105 disposed behind the reflection sheet 104, and a base metalsheet 106 disposed behind the panel metal sheet 105 (FIGS. 21, 22). Theliquid crystal image display device 1 also includes an optical sensor112 that measures light from the back surface of the reflection sheet104, a substrate 111 having the optical sensor 112 thereon, and atubular cushion 113 for preventing the entry of external light into theoptical sensor 112 (FIGS. 21, 22). The substrate 111 is mounted in sucha manner to block a through hole 1061 of the base metal sheet 106, andthe tubular cushion 113 is mounted in such a manner to block a lightinghole 1051 of the panel metal sheet 105 (FIGS. 21, 22).

Through an investigation, the present investors found a model as shownin FIG. 22. In this model, when the liquid crystal panel modules 102 to105 were heated, the reflection sheet 104 became distorted in adirection opposite to that in FIG. 21, that is, the center of thereflection sheet 104 moved forward (toward the front); the gap waschanged from S1 to S2; and thus the amount of light entering the opticalsensor 112 increased. The present investors also found a model as shownin FIG. 21. In this model, when the liquid crystal panel modules 102 to105 were heated, the reflection sheet 104 became distorted in adirection opposite to that in FIG. 22, that is, the center of thereflection sheet 104 moved backward (toward the back); the gap waschanged from S2 to S1; and thus the amount of light entering the opticalsensor 112 decreased. The present inventors then found that the amountof light from the reflection sheet 104 increased or decreased accordingto the presence or absence of the gap or the size of the gap and thusthe correlation between the change in the luminance of the liquidcrystal display panel 102 and the value measured by the optical sensor112 varied.

As described above, liquid crystal image display devices are increasingin screen size or slimming, and the amount of deformation of thereflection sheet is thought to be increasing accordingly. However, themanner that the deformation changes with the temperature, externalforce, or the like is difficult to predict. As a result, the correlationbetween the change in the luminance of the liquid crystal display paneland the value measured by the optical sensor varies.

Accordingly, an object of the present invention is to provide an opticalsensor mounting structure which is used in an image display device andin which the gap between a reflection sheet and a tubular cushion forpreventing the entry of external light into an optical sensor iseliminated so that the amount of light from a backlight can be measuredaccurately.

Solution to Problem

The present invention provides an optical sensor mounting structure foruse in image display devices. The structure includes an optical sensorconfigured to measure light from a back surface of a reflection sheet inan image display device, a substrate having the optical sensor thereon,and a tubular cushion for preventing entry of external light into theoptical sensor. A front surface of the tubular cushion and thereflection sheet are bonded together, and a back surface of the tubularcushion and the substrate are bonded together.

According to the present invention, the gap between the tubular cushionand reflection sheet is eliminated so that the amount of light from thebacklight can be measured accurately. Specifically, since the front andback surfaces of the tubular cushion are bonded to predeterminedpositions, the distance between the area serving as a measurement lightsource on the back surface of the reflection sheet and the opticalsensor is kept constant. The size of the area serving as a measurementlight source on the back surface of the reflection sheet is also keptconstant. Thus, the amount of light from the backlight can be measuredaccurately.

Examples of the configuration for eliminating the gap between thetubular cushion and reflection sheet include the above configuration, aswell as an optical sensor mounting structure which is used in an imagedisplay device and which includes an optical sensor configured tomeasure light from a back surface of a reflection sheet in the imagedisplay device, a substrate having the optical sensor thereon, and atubular cushion for preventing entry of external light into the opticalsensor. In this optical sensor mounting structure, a base metal sheethaving a light-receiving hole through which the optical sensor receiveslight is disposed over the back surface of the reflection sheet; thesubstrate is mounted on the base metal sheet; a front surface of thetubular cushion and the reflection sheet are bonded together; and a backsurface of the tubular cushion and the base metal sheet are bondedtogether.

Examples of the configuration in which the substrate and the backsurface of the tubular cushion are bonded together include aconfiguration in which the substrate and the back surface of the tubularcushion are bonded together and a configuration in which a substrateunit including the substrate and a frame surrounding the substrate, andthe back surface of the tubular cushion are bonded together. Examples ofthe configuration in which the substrate is mounted on the base metalsheet include a configuration in which the substrate is mounted on thebase metal sheet by fixing means such as an adhesive, a double-sidedtape, or a screw, a configuration in which a substrate unit includingthe substrate and a frame surrounding the substrate is mounted on thebase metal sheet by fixing means such as an adhesive, a double-sidedtape, or a screw, and a configuration in which the substrate is mountedover the base metal sheet with a cushion member therebetween.

Examples of an adhesive include a rubber-based adhesive, anacrylic-based adhesive, and an epoxy-based adhesive. If a double-sidedtape is used, the above bonding can be easily performed by stickingdouble-sided tapes to the front and back surfaces of the tubularcushion.

The tubular cushion is in the shape of, for example, a cylindrical tube,a rectangular tube, a hexagonal tube, or other polygonal tubes. Examplesof the material of the tubular cushion include a rubber material such asurethane or silicone and a sponge foam formed of a rubber material suchas urethane or silicone. Other known cushion materials may be used.

The substrate having the optical sensor thereon may be an opticalsensor-packaged substrate or a plate for positioning the optical sensor.

In the present invention, a panel metal sheet is preferably disposedbehind the reflection sheet; there is preferably further included asecond cushion disposed outside the tubular cushion serving as a firstcushion and configured to support the substrate; a front surface of thesecond cushion and the panel metal sheet are preferably bonded together;and/or a back surface of the second cushion and the substrate arepreferably bonded together.

According to the present invention, the substrate is supported morestably.

Examples of the configuration in which the substrate is supported morestably include the above configuration, as well as an optical sensormounting structure which is used in an image display device and in whicha panel metal sheet is disposed behind the reflection sheet; a basemetal sheet is disposed behind the panel metal sheet; there is furtherincluded a second cushion disposed outside the tubular cushion servingas a first cushion and configured to support the substrate; and a frontsurface of the second cushion and the substrate are bonded togetherand/or a back surface of the second cushion and the base metal sheet arebonded together.

The tubular cushion is formed of, rubber, elastomer, or the like. Morespecifically, it is formed of polyethylene sponge, urethane sponge, orthe like. To improve light-shielding performance, as well as to allowthe tubular cushion to contact the reflection sheet softly, aclosed-cell sponge is preferably used as the tubular cushion. Thetubular cushion is bonded to the reflection sheet using a double-sidedtape, adhesive, pressure-sensitive adhesive, or the like. Note that thetubular cushion member is not limited to a tubular cushion member whichis hollowed and molded in one piece. A tubular cushion member formed bybonding multiple block-shaped sponges together may be used as long aslight-shielding performance can be maintained.

Examples of an adhesive include a rubber-based adhesive, anacrylic-based adhesive, and an epoxy-based adhesive. If a double-sidedtape is used, the above bonding can be easily performed by stickingdouble-sided tapes to the front and back surfaces of the respectivecushions (first cushion, second cushion).

The respective cushions (first cushion, second cushion) are in the shapeof, for example, a cylindrical tube, a rectangular tube, a hexagonaltube, or other polygonal tubes. Multiple block-shaped cushions such asprismatic cushions or cylindrical cushions may be disposed. Examples ofthe material of the cushions (first cushion, second cushion) include asponge foam formed of a rubber material such as urethane or silicone.Other known cushion materials may be used.

In the configuration in which the first and second cushions areincluded, rubber hardness of the second cushion is preferably lower thanrubber hardness of the first cushion.

According to the present invention, the first cushion keeps the distancebetween the optical sensor and reflection sheet constant, and the secondcushion allows the optical sensor and reflection sheet to easily followthe displacement of the substrate caused by the warpage or deformationof the panel metal sheet or base metal sheet.

In the configuration in which the panel metal sheet is included, alighting hole is preferably formed in the panel metal sheet, and thefirst cushion is preferably contactlessly disposed in the panel metalsheet.

According to the present invention, due to the first cushion, thedistance between the optical sensor and reflection sheet isinsusceptible to the displacement of the substrate caused by the warpageor deformation of the panel metal sheet. That is, the first cushionkeeps the distance between the optical sensor and reflection sheetconstant.

The shape of the lighting hole of the panel metal sheet may be a circle,an oval, a rectangle, a hexagon, or other polygons. The lighting holemay be formed in the center of the panel metal sheet or may be formedadjacent to an edge thereof. The present invention is also applied to aconfiguration in which a small hole for measuring light is formed in thereflection sheet. The shape of the small hole in the reflection sheetmay be a circle, an oval, a rectangle, a hexagon, or other polygons. Thesmall hole may be formed in the center of the reflection sheet or may beformed adjacent to an edge thereof.

The present invention also provides an optical sensor mounting structurefor use in image display devices. The structure includes an opticalsensor configured to measure light from a back surface of a reflectionsheet in an image display device, a substrate having the optical sensorthereon, and a tubular cushion for preventing entry of external lightinto the optical sensor. A base metal sheet having a light-receivinghole through which the optical sensor receives light is disposed over aback surface of the reflection sheet; the substrate is mounted on thebase metal sheet; the tubular cushion includes first and second tubularmembers; a front surface of the first tubular member and the reflectionsheet are bonded together; and a back surface of the second tubularmember and the base metal sheet are bonded together.

According to the present invention, even in the configuration in whichthe substrate is mounted on the base metal sheet, the gap between thetubular cushion and reflection sheet is eliminated so that the amount oflight from the backlight can be measured accurately.

The shape of the light-receiving hole in the base metal sheet may be acircle, an oval, a rectangle, a hexagon, or other polygons. Thelight-receiving hole may be formed in the center of the base metal sheetor may be formed adjacent to an edge thereof.

In the present invention, a panel metal sheet is preferably disposedbehind the reflection sheet; the base metal sheet is preferably disposedbehind the panel metal sheet; a lighting hole is preferably formed inthe panel metal sheet; and the first tubular member is preferablycontactlessly disposed in the panel metal sheet.

According to the present invention, the first tubular member keeps thedistance between the optical sensor and reflection sheet constantwithout being affected by the displacement associated with the warpageor deformation of the panel metal sheet.

In the present invention, there is preferably further included asheet-shaped connecting member bonding together the first tubularmember, the second tubular member, and the panel metal sheet.

According to the present invention, the respective members are connectedand fixed to each other by the connecting member. Thus, the distancebetween the optical sensor and reflection sheet is easily kept constant,and the amount of light from the backlight is measured accurately withease.

The shape of the connecting member may be a circle, a rectangle, ahexagon, or other polygons. The material of the connecting member may bea paper sheet, a resin sheet, a metal sheet, or the like. For example, adouble-sided tape may be used as the connecting member.

In the present invention, rubber hardness of the second tubular memberis preferably lower than rubber hardness of the first tubular member.According to the present invention, the second tubular memberfacilitates the following of the displacement associated with thewarpage or deformation of the panel metal sheet or base metal sheet.

Examples of an image display panel in the image display device include aliquid crystal display panel. In a liquid crystal image display device,a backlight is disposed behind a liquid crystal display panel; areflection sheet is disposed behind the backlight; a panel metal sheetis disposed behind the reflection sheet; and a base metal sheet isdisposed behind the panel metal sheet.

The present invention also provides an image display device includingany one of the above optical sensor mounting structures for use in imagedisplay devices. In the image display device, light from a back surfaceof a reflection sheet disposed behind a backlight is measured to controlluminance of the backlight.

According to the present invention, there is provided a high-qualityimage display device that accurately measures the amount of light fromthe backlight to control the luminance of the backlight.

Advantageous Effects of Invention

According to the present invention, the front and back surfaces of thetubular cushion are bonded to the respective predetermined positions.Thus, the distance between the area serving as a measurement lightsource on the back surface of the reflection sheet and the opticalsensor is kept constant. The area of the area serving as a measurementlight source on the back surface of the reflection sheet is also keptconstant. As a result, the amount of light from the backlight can bemeasured accurately.

According to the present invention, there is provided a high-qualityimage display device that accurately measures the amount of light fromthe backlight to control the luminance of the backlight. Further, therecan be provided an image display device including the optical sensormounting, structure of the present invention without making a largechange to the design.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of an image display device including anoptical sensor mounting structure of the present invention.

FIG. 2 is a main part sectional view of an image display device of anembodiment of the present invention seen from above.

FIG. 3 is a main part sectional view of the image display device of theabove embodiment seen from above and is a view at a differenttemperature.

FIG. 4 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 5 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 6 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 7 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 8 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 9 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 10 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 11 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 12 is an exploded main part perspective view showing the positionalrelationships among components in the image display device of the aboveembodiment.

FIG. 13A is a diagram showing a front view of a tubular cushion of theimage display device of the above embodiment.

FIG. 13B is a diagram showing a side view of a tubular cushion of theimage display device of the above embodiment.

FIG. 13C is a diagram showing a rear view of a tubular cushion of theimage display device of the above embodiment.

FIG. 14 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 15A is a diagram showing a front view of a tubular cushion of theimage display device of the above embodiment.

FIG. 15B is a diagram showing a side view of a tubular cushion of theimage display device of the above embodiment.

FIG. 15C is a diagram showing a rear view of a tubular cushion of theimage display device of the above embodiment.

FIG. 16 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 17 is a main part sectional view of an image display device ofanother embodiment seen from above.

FIG. 18A is a diagram showing a front view of a tubular cushion of theimage display device of the above embodiment.

FIG. 18B is a diagram showing a side view of a tubular cushion of theimage display device of the above embodiment.

FIG. 18C is a diagram showing a rear view of a tubular cushion of theimage display device of the above embodiment.

FIG. 19A is a diagram showing a front view of another example of thetubular cushion of the image display device of the above embodiment.

FIG. 19B is a diagram showing a side view of another example of thetubular cushion of the image display device of the above embodiment.

FIG. 19C is a diagram showing a rear view of another example of thetubular cushion of the image display device of the above embodiment.

FIG. 20 is a schematic front view of a traditional liquid crystal imagedisplay device.

FIG. 21 is a main part sectional view of the traditional liquid crystalimage display device seen from above.

FIG. 22 is a main part sectional view of the traditional liquid crystalimage display device seen from above and is a view at a differenttemperature.

DESCRIPTION OF EMBODIMENTS

Now, embodiments of the present invention will be described withreference to the drawings.

Embodiments of Present Invention

FIG. 1 is a schematic front view of an image display device including,an optical sensor mounting structure of the present invention.Hereafter, a liquid crystal image display device 1 will be described asan example.

First Embodiment

FIGS. 2 and 3 are sectional views taken along line A-A of FIG. 1 and aremain part sectional views of a liquid crystal image display device 1 ofan embodiment of the present invention seen from above. FIGS. 2 and 3show that a reflection sheet 104 becomes distorted in different mannersat different temperatures. Specifically, FIG. 3 shows an example inwhich when liquid crystal panel modules 102 to 105 are heated, thereflection sheet 104 becomes distorted in a direction opposite to thatin FIG. 2, that is, the center of the reflection sheet 104 moves forward(toward the front). FIG. 2 shows an example in which when the liquidcrystal panel modules are heated, the reflection sheet 104 becomesdistorted in a direction opposite to that in FIG. 3, that is, the centerof the reflection sheet 104 moves backward (toward the back). However,the manner that the reflection sheet 104 becomes warped or deformed withthe temperature is not limited to the above examples and varies amongmodels.

The liquid crystal image display device 1 of the present embodimentincludes a liquid crystal display panel 102, a backlight 103 disposedbehind the liquid crystal display panel 102, the reflection sheet 104disposed behind the backlight 103, a panel metal sheet 105 disposedbehind the reflection sheet 104, and a base metal sheet 106 disposedbehind the panel metal sheet 105 (FIGS. 2, 3). The liquid crystal imagedisplay device 1 also includes an optical sensor 12 that measures lightfrom the back surface of the reflection sheet 104, a substrate 11 havingthe optical sensor 12 thereon, and a tubular cushion 13 for preventingthe entry of external light into the optical sensor 12. The substrate 11is mounted on the base metal sheet 106 in such a manner that it blocks athrough hole 1061 of the base metal sheet 106 (FIGS. 2, 3). Thesubstrate 11 is mounted on the base metal sheet 106 by fixing means suchas an adhesive, double-sided tape, or screw. The substrate 11 may bemounted over the base metal sheet 106 with a cushion membertherebetween. In the examples shown in FIGS. 2 and 3, the substrate 11is bonded to the base metal sheet 106 using an adhesive 1101. Thetubular cushion 13 is contactlessly inserted in a lighting hole 1051 ofthe panel metal sheet 105 (FIGS. 2, 3).

In the present embodiment, the front surface of the tubular cushion 13is bonded to the reflection sheet 104, and the back surface thereof isbonded to the substrate 11 (FIGS. 2, 3). FIG. 13 includes diagramsshowing the tubular cushion 13 of the present embodiment, in which FIG.13A is a front view; FIG. 13B is a side view; and FIG. 13C is a rearview. The tubular cushion 13 has a double-sided tape 1301 stuck to thefront surface thereof and a double-sided tape 1302 stuck to the backsurface thereof. The tubular cushion 13 has a cylindrical shape and ismade of a sponge foam formed of a rubber material such as urethane orsilicone. While the tubular cushion 13 is bonded to the reflection sheet104 and substrate 11 using the double-sided tapes 1301 and 1302 in thepresent embodiment, it may be bonded thereto using other means. Forexample, an adhesive such as a rubber-based adhesive, acrylic-basedadhesive, or epoxy-based adhesive may be used.

According to the present embodiment, the front surface of the tubularcushion 13 is bonded to the reflection sheet 104, and the back surfacethereof is bonded to the substrate 11. Thus, the gap between the tubularcushion 13 and reflection sheet 104 is eliminated so that the amount oflight from the backlight 103 can be measured accurately. Specifically,since the front and back surfaces of the tubular cushion 13 are bondedto the predetermined positions, the distance between the area serving asa measurement light source on the back surface of the reflection sheet104 and the optical sensor 12 is kept constant. The area of the areaserving as a measurement light source on the back surface of thereflection sheet 104 is also kept constant. Thus, the amount of lightfrom the backlight 103 can be measured accurately.

Second Embodiment

FIG. 4 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiment denote the same functions and thereforedescription thereof will be omitted as appropriate. In the presentembodiment, a substrate 11 is bonded to a base metal sheet 106. Thefront surface of a tubular cushion 13 is bonded to a reflection sheet104, and the back surface thereof is bonded to the base metal sheet 106(FIG. 4). According to the present embodiment, a small hole only has tobe formed as a through hole 1061 of the base metal sheet 106, and thesubstrate 11 is supported strongly with ease.

Third Embodiment

FIG. 5 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, a substrate 11 is mounted on a panel metal sheet 105(FIG. 5). According to the present embodiment, the distance from thelight source to an optical sensor 12 is reduced. Thus, the amount oflight from the backlight 103 can be measured accurately with ease evenwhen the amount of light is small.

Fourth Embodiment

FIG. 6 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, the length of a substrate 11 is set to a smallersize than the diameter of a lighting hole 1051 of a panel metal sheet105 (FIG. 6). According to the present embodiment, the substrate 11 isinsusceptible to the warpage or deformation of the panel metal sheet105.

Fifth Embodiment

FIG. 7 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, the back surface of a tubular cushion 13 is flanged,and a substrate 11 is mounted over a base metal sheet 106 with theflanged part of the tubular cushion 13 therebetween (FIG. 7). Accordingto the present embodiment, the flanged part of the tubular cushion 13serves as a cushion member. Thus, the substrate 11 is insusceptible tothe warpage or deformation of the base metal sheet 106, as well as isless likely to be displaced.

Sixth Embodiment

FIG. 8 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, the back surface of a tubular cushion 13 is flanged,and a substrate 11 is mounted over a panel metal sheet 105 with theflanged part of the tubular cushion 13 therebetween (FIG. 8). Accordingto the present embodiment, the flanged part of the tubular cushion 13serves as a cushion member. Thus, the substrate 11 is insusceptible tothe warpage or deformation of the panel metal sheet 105, as well as isless likely to be displaced.

Seventh Embodiment

FIG. 9 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, in addition to a tubular cushion 13, a cylindricalcushion 14 is disposed. The inner diameter of the cylindrical cushion 14is set to a larger size than the outer diameter of the tubular cushion13. The cylindrical cushion 14 has double-sided tapes 1401 and 1402stuck to the front and back surfaces, respectively, thereof. The frontsurface of the cylindrical cushion 14 is bonded to a panel metal sheet105, and the back surface thereof is bonded to the substrate 11.According to the present embodiment, the cylindrical cushion 14 servesas a cushion member. Thus, the substrate 11 is insusceptible to thewarpage or deformation of the panel metal sheet 105, as well as is lesslikely to be displaced. Another configuration may be employed in whichonly the front surface of the cylindrical cushion 14 is bonded, and theback surface thereof is not bonded. Yet another configuration may beemployed in which only the back surface of the cylindrical cushion 14 isbonded, and the front surface thereof is not bonded.

Eighth Embodiment

FIG. 10 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, in addition to a tubular cushion 13, a cylindricalcushion 15 is disposed. The inner diameter of the cylindrical cushion 15is set to a larger size than the outer diameter of the tubular cushion13. The cylindrical cushion 15 has double-sided tapes 1501 and 1502stuck to the front and back surfaces, respectively, thereof. The frontsurface of the cylindrical cushion 15 is bonded to a substrate 11, andthe back surface thereof is bonded to a base metal sheet 106. Accordingto the present embodiment, the cylindrical cushion 15 serves as acushion member. Thus, the substrate 11 is insusceptible to the warpageor deformation of the base metal sheet 106, as well as is less likely tobe displaced. Another configuration may be employed in which only thefront surface of the cylindrical cushion. 15 is bonded, and the backsurface thereof is not bonded. Yet another configuration may be employedin which only the back surface of the cylindrical cushion 15 is bonded,and the front surface thereof is not bonded.

Ninth Embodiment

FIG. 11 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. FIG. 12 is an explodedmain part perspective view showing the positional relationships amongcomponents in the example shown in FIG. 11. The same reference signs asthose in the above embodiments denote the same functions and thereforedescription thereof will be omitted as appropriate. In the presentembodiment, two block-shaped cushions 114 are bonded to the frontsurface of a substrate 11 at a predetermined interval in such a mannerto be located on both sides of the tubular cushion 13. Similarly, twoblock-shaped cushions 115 are bonded to the back surface of thesubstrate 11 at a predetermined interval in such a manner to be locatedon both sides of the tubular cushion 13 (FIGS. 11, 12). Morespecifically, the front surfaces of the block-shaped cushions 114 arebonded to the back surface of a panel metal sheet 105, and the backsurfaces thereof are bonded to the front surface of the substrate 11.Similarly, the front surfaces of the block-shaped cushions 115 arebonded to the back surface of the substrate 11, and the back surfacesthereof are bonded to the front surface of a base metal sheet 106 (FIGS.11, 12). According to the present embodiment, the substrate 11 isinsusceptible to the warpage or deformation of the panel metal sheet105, as well as is less likely to be displaced. Further, the sizes ofthe block-shaped cushions 114 and 115 can be suited to that of thesubstrate 11, for example, by cutting them as appropriate. For theblock-shaped cushions 114, there may be employed a configuration inwhich only the front surfaces of the cushions 114 are bonded, and theback surfaces thereof are not bonded, or a configuration in which onlythe back surfaces of the cushions 114 are bonded, and the front surfacesthereof are not bonded. For the tubular cushions 115, there may beemployed a configuration in which only the front surfaces of thecushions 115 are bonded, and the back surfaces thereof are not bonded,or a configuration in which only the back surfaces of the cushions 115are bonded, and the front surfaces thereof are not bonded.

Hereafter, the tubular cushion 13 will be referred to as a firstcushion, and the cushions 14, 114, and 115, which are disposed outsidethe first cushion and support the substrate 11, will be referred to assecond cushions. The rubber hardness of the second cushions 14, 114, and115 is set to a lower degree than that of the first cushion 13.

According to the present embodiment, the first cushion 13 keeps thedistance between the light source and optical sensor 12 constant.Further, the second cushions 14, 114, and 115 serve as buffer memberswhen the panel metal sheet 105 or base metal sheet 106 vibrates, forexample, when receiving an external force. Thus, the substrate 11 isinsusceptible to the vibration or the like of the panel metal sheet 105or base metal sheet 106, as well as is less likely to be displaced.

While the lighting hole 1051 of the panel metal sheet 105 is in theshape of a circle in the example shown in FIG. 12, it may be in othershapes. For example, the lighting hole 1051 may be in the shape of anoval, a rectangle, a hexagon, or other polygons. The lighting hole 1051may be disposed in the center of the panel metal sheet 105 or may bedisposed adjacent to an edge thereof. The present invention is notlimited to the above configuration and is also applied to aconfiguration in which a small hole for measuring light is formed in thereflection sheet 104. The small hole formed in the reflection sheet 104is in the shape of, for example, a circle, an oval, a rectangle, ahexagon, or other polygons. The small hole may be formed in the centerof the reflection sheet or may be formed adjacent to an edge thereof.

Tenth Embodiment

FIG. 14 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. FIG. 15includes diagrams showing a tubular cushion 13 of the presentembodiment, in which FIG. 15A is a front view; FIG. 15B is a side view;and FIG. 15C is a rear view. The tubular cushion 13 has a constrictedpart 1350 on the side surface thereof [FIG. 15B]. The tubular cushion 13is formed of a rubber material such as urethane or silicone or made of asponge foam formed of a rubber material such as urethane or silicone.The tubular cushion 13 has a double-sided tape 1301 stuck to the frontsurface thereof and a double-sided tape 1302 stuck to the back surfacethereof.

In the examples shown in FIGS. 14 and 15, the outer diameter of theconstricted part 1350 on the side surface of the tubular cushion 13 isset to a size identical or close to the diameter of the lighting hole1051 of a panel metal sheet 105. The width (vertical length) of theconstricted part 1350 on the side surface of the tubular cushion 13 isalso set to a size identical or close to the thickness of the panelmetal sheet 105. In the present embodiment, the constricted part 1350 ofthe tubular cushion 13 is fitted in the lighting hole 1051 of the panelmetal sheet 105 (FIG. 14). The front surface of the tubular cushion 13is bonded to a reflection sheet 104, and the back surface thereof isbonded to the substrate 11 (FIG. 14). According to the presentembodiment, the tubular cushion 13 is easy to mount, since theconstricted part 1350 thereof is fitted into the lighting hole 1051 ofthe panel metal sheet 105. Further, the parts higher and lower than theconstricted part 1350 serve as buffer members. Thus, the substrate 11 isinsusceptible to the warpage or deformation of the panel metal sheet105, as well as is less likely to be displaced.

Eleventh Embodiment

FIG. 16 is a main part sectional view of a liquid crystal image displaydevice 1 of an eleventh embodiment seen from above. The same referencesigns as those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate. In thepresent embodiment, a tubular cushion 13 has two constricted partsformed on the side surface thereof at a predetermined interval (see FIG.16). According to the present embodiment, the upper constricted part ofthe tubular cushion 13 is fitted in a through hole 1061 of a base metalsheet 106, and the lower constricted part thereof is fitted in alighting hole 1051 of a panel metal sheet 105. The parts higher andlower than these constricted parts serve as cushion members. Thus, thesubstrate 11 is insusceptible to the warpage or deformation of the basemetal sheet 106 and panel metal sheet 105, as well as is less likely tobe displaced.

Twelfth Embodiment

FIG. 17 is a main part sectional view of a liquid crystal image displaydevice 1 of another embodiment seen from above. The same reference signsas those in the above embodiments denote the same functions andtherefore description thereof will be omitted as appropriate.

The liquid crystal image display device 1 of the present embodimentincludes a liquid crystal display panel 102, a backlight 103 disposedbehind the liquid crystal display panel 102, a reflection sheet 104disposed behind the backlight 103, a panel metal sheet 105 disposedbehind the reflection sheet 104, and a base metal sheet 106 disposedbehind the panel metal sheet 105 (FIG. 17). The liquid crystal imagedisplay device 1 also includes an optical sensor 12 that measures lightfrom the back surface of the reflection sheet 104, a substrate 11 havingthe optical sensor 12 thereon, and a tubular cushion 13 for preventingthe entry of external light into the optical sensor 12. The substrate 11is mounted over the base metal sheet 106 with two block-shaped cushions116 disposed at a predetermined interval therebetween (FIG. 17). Thesubstrate 11 is mounted over the base metal sheet 106 in such a mannerto block a light-receiving hole 1062 of the base metal sheet 106. Thetubular cushion 13 is contactlessly inserted in a lighting hole 1051 ofthe panel metal sheet 105 (FIG. 17). The cushions 116 are formed of aninsulating material.

In the liquid crystal image display device 1 of the present embodiment,the front surface of the tubular cushion 13 is bonded to the reflectionsheet 104, and the back surface thereof is bonded to the front surfaceof the base metal sheet 106 (FIG. 17). FIG. 18 includes diagrams showingthe tubular cushion 13 of the present embodiment, in which FIG. 18A is afront view; FIG. 18B is a side view; and FIG. 18C is a rear view. Thetubular cushion 13 includes a first tubular member 131, a second tubularmember 132, and a sheet-shaped connecting member 133 connecting thesetubular members by bonding. The inner diameter of the second tubularmember 132 is set to a larger size than the outer diameter of the firsttubular member 131, and the outer diameter of the connecting member 133is set to a larger size than the outer diameter of the second tubularmember 132 [FIG. 17, FIGS. 18(a), 18(b), and 18(c)]. The tubular cushion13 of the present embodiment has a double-sided tape 1321 stuck to thefront surface of the first tubular member 131 and a double-sided tape1331 stuck to the front back surface of the connecting member 133.Further, a double-sided tape 1322 is stuck to the back surface of thesecond tubular member 132 [FIG. 18B]. The tubular cushion 13 is formedby combining sponge foams formed of a rubber material such as urethaneor silicone. The connecting member 133 is formed of an insulatingmaterial.

In the present embodiment, the front surface of the first tubular member131 of the tubular cushion 13 is bonded to the reflection sheet 104using the double-sided tape 1321, and the back surface of the secondtubular member 132 of the tubular cushion 13 is bonded to the base metalsheet 106 using the double-sided tape 1322. (FIG. 17). Further, usingthe double-sided tape 1331, the front surface of the connecting member133 of the tubular cushion 13 is bonded to the first tubular member 131,as well as is bonded to the back surface of the panel metal sheet 105.Furthermore, the back surface of the connecting member 133 of thetubular cushion 13 is bonded to the second tubular member 132 of thetubular cushion 13 using a double-sided tape (no reference sign).

According to the present embodiment, the gap between the tubular cushion13 and reflection sheet 104 is eliminated in a state in which thesubstrate 11 is mounted over the base metal sheet 106 in a mannerinsulated from each other. Thus, the amount of light from the backlight103 can be measured accurately. Specifically, since the front surface(1321), the central connecting part (1331), and the back surface of thetubular cushion 13 are bonded to the respective predetermined positions,the distance between the area serving as a measurement light source onthe back surface of the reflection sheet 104 and the optical sensor 12is kept constant. The size of the area serving as a measurement lightsource on the back surface of the reflection sheet 104 is also keptconstant. Further, the members 131, 132, and 133 forming the tubularcushion 13 serve as buffer members. Thus, the substrate 11 isinsusceptible to the warpage or deformation of the base metal sheet 106and panel metal sheet 105. As a result, the amount of light from thebacklight 103 can be measured accurately.

FIG. 19 includes diagrams showing another example of the tubular cushion13 of the present embodiment, in which FIG. 19A is a front view; FIG.19B is a side view; and FIG. 19C is a rear view. In the tubular cushion13 of this example, the connecting member 133 has a rectangular shape.

Examples of the shape of the connecting member 133 include a circle, arectangle, a hexagon, and other polygons. Examples of the material ofthe connecting member 133 include a paper sheet, a resin sheet, and ametal sheet. More specifically, a double-sided tape may be used as theconnecting member 133.

In the present embodiment, the rubber hardness of the second tubularmember 132 is set to a lower degree than that of the first tubularmember 131. According to the present embodiment, the substrate 11 isinsusceptible, to the vibration or the like of the panel metal sheet 105or base metal sheet 106, as well as is less likely to be displaced.

While the tubular cushion 13 are composed of the first tubular member131, the second tubular member 132, and the sheet-shaped connectingmember 133 connecting these tubular members by bonding in the presentembodiment, this configuration is illustrative only. For example, thetubular cushion 13 may be molded in one piece.

The present invention is not limited to the above embodiments. Thebonding means is not limited to the double-sided tapes, and any bondingmeans may be used as long as it can eliminate the gap between thetubular cushion 13 and reflection sheet 104. For example, an adhesivesuch as a rubber-based adhesive, acrylic-based adhesive, or epoxy-basedadhesive may be used. The shape of the tubular cushion 13 is not limitedto the cylindrical shape. The tubular cushion may be in any shape aslong as it can prevent the entry of external light into the opticalsensor 12 so that light from the back surface of the reflection sheet104 can be measured accurately. For example, the tubular cushion may bein the shape of a rectangle tube, hexagon tube, or other polygonaltubes. The optical sensor mounting structure of the present inventionmay be incorporated into an image display device which is beingassembled, or may be retrofitted into an assembled image display device.As seen above, changes can be made to the present invention asappropriate without departing from the spirit and scope of theinvention.

DESCRIPTION OF NUMERALS

-   1 image display device (liquid crystal image display device)-   11 substrate-   12 optical sensor-   13 tubular cushion (first cushion)-   14 tubular cushion (second cushion)-   114, 115, 116 block-shaped cushion (second cushion)-   102 image display panel (liquid crystal display panel)-   103 backlight-   104 reflection sheet-   105 panel metal sheet-   106 base metal sheet-   1051 lighting hole-   1061 through hole-   1301, 1302, 1401, 1402 double-sided tape (adhesive)

The invention claimed is:
 1. An optical sensor mounting structure foruse in image display devices comprising: an optical sensor configured tomeasure light from a back surface of a reflection sheet in an imagedisplay device; a substrate having the optical sensor thereon; a tubularcushion for preventing entry of external light into the optical sensor;and a second cushion disposed outside the tubular cushion serving as afirst cushion and configured to support the substrate; wherein a panelmetal sheet is disposed behind the reflection sheet; wherein a frontsurface of the tubular cushion and the reflection sheet are bondedtogether; wherein a back surface of the tubular cushion and thesubstrate are bonded together; wherein the structure further comprisesone or both of configurations (1) and (2): (1) a front surface of thesecond cushion and the panel metal sheet are bonded together; (2) a backsurface of the second cushion and the substrate are bonded together. 2.The optical sensor mounting structure of claim 1, wherein rubberhardness of the second cushion is lower than rubber hardness of thefirst cushion.
 3. The optical sensor mounting structure of claim 1,wherein a lighting hole is formed in the panel metal sheet, and thefirst cushion is contactlessly disposed in the panel metal sheet.